README.md in ahoy_email-0.2.3 vs README.md in ahoy_email-0.2.4

@@ -112,10 +112,18 @@
 
 ```html
 <a data-skip-utm-params="true" href="...">Break it down</a>
 ```
 
+### Extra Attributes
+
+Create a migration to add extra attributes to the `ahoy_messages` table and use:
+
+```ruby
+track extra: {campaign_id: 1}
+```
+
 ## Customize
 
 ### Tracking
 
 Skip tracking of attributes by removing them from your model.  You can safely remove:
@@ -215,9 +223,15 @@
 Use a different model
 
 ```ruby
 AhoyEmail.message_model = UserMessage
 ```
+
+## Upgrading
+
+### 0.2.3
+
+Optionally, you can store UTM parameters by adding `utm_source`, `utm_medium`, and `utm_campaign` columns to your message model.
 
 ## History
 
 View the [changelog](https://github.com/ankane/ahoy_email/blob/master/CHANGELOG.md)